Abstract: In order to graft amidoxime onto the surface of carbon spheres, amidoxime-rich carbon spheres(HTC-AO) has been synthesized via hydrothermal carbonization of acrylonitrile grafted starch, which was used for the removal of U(Ⅵ) from aqueous solution. The pH of initial aqueous solution at 6.0 is in favour of adsorption of uranium. The adsorption capacity of HTC-AO is 455.6 mg/g. In addition, the adsorption of uranium ions could be well-described by the Langmuir isotherms and pseudo-second kinetic models. And thermodynamic parameters indicate the adsorption process is feasible, endothermic and spontaneous. Selective adsorption studies show that the HTC-AO has a high selective for U(Ⅵ) in the presence of co-existing ions.